Date of Award

5-31-2017

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Alan D. Christian

Second Advisor

Robyn E. Hannigan

Third Advisor

Helen Poynton

Abstract

The River Continuum Concept (RCC) is a conceptual model of the expected relationship between the surrounding physical habitat of a watershed, the streams that are part of the watershed, and the in-stream biota and fauna. The concept illustrates a river’s chemical, biological, and physical characteristics, the influence and relation of these characteristics to each other, and the way these characteristics change downstream. Due to the influential relationship of the characteristics on one another, under the RCC framework a river’s biological community is expected to be somewhat predictable in response to basal resources in the food web. Anthropogenic landscape alteration, including land use and land cover (LULC) change, influences organic matter production and delivery, stream assemblages and ecosystem processes, and may alter general RCC expectations in response to altered conditions. Meanwhile, river restoration can play an important role in counteracting LULC effects and re-establishing relationships between physical structure, food web inputs, and biota associated with the RCC.

Tidmarsh Farms Study Area (TFSA), including Beaver Dam Brook (BDB) and its surrounding wetland, was actively farmed for cranberries from the late-1800s until 2010. Intensive farming of this type represents a significant change to land cover and use, and I expected to find associated changes to stream habitat quality and resident biota as compared to less altered settings. With active restoration activities scheduled to commence at TFSA in 2016 – including dam removals, channel reconstruction, large wood installation, and more - my research sought to comprehensively establish baseline conditions, provide a basis for future post-restoration comparison, and test our expectations about agricultural impacts to stream ecosystem condition and potential differences in the RCC.

Within the TFSA, I established 8 sampling stations along 1st - 3rd order stream reaches of BDB and sampled for physical habitat, physical-chemical water column, benthic macro invertebrates (BMI), and nutrient limitation. While BDB used to be a forested wetland environment, BDB is no longer a forested headwater system due to agricultural alterations to the landscape over the past 100+ years. Because of this, I expected the stream structure and function within the TFSA headwaters not follow RCC “pristine” closed canopy expectations, but to reflect more of an open canopy system. As expected, I found overall homogeneity across TFSA in terms of physical, chemical, and biological characteristics. The influence of agricultural activities was apparent at the majority of stations and differences within the TFSA were only somewhat apparent at the “extremes” of upstream versus downstream study area stations. Overall, the homogeneity of the study area physical habitat and available resources appears to drive a simplified benthic macroinvertebrate community.

Comments

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